Update tests to run on PHP 8.1, 8.0 and 7.0

Author: rbibby

.github/workflows/run-tests.yml

@@ -14,7 +14,7 @@ jobs:
 
         strategy:
             matrix:
-                php: [7.4, 7.3, 7.2, 7.1, 5.6]
+                php: [8.1, 8.0, 7.4, 7.3, 7.2, 7.1, 7.0, 5.6]
 
         name: PHP${{ matrix.php }} - ubuntu-latest